Method op making white light holograms



DEF. PUB.

Ea A ril 15, 1969 J. 5. HARPER ETA!- METHOD OF MAKING WHITE LIGHT HOLOGRAMS Filed Jan. 15, 1968 T661025 QRJIN as/gm DEFENSIVE PUBLICATION UNITED STATES PATENT OFFICE Published at the request of the applicant or owner in accordance with the Notice of Apr. 11, 1968, 849 O.G. 1221. Identification is by serial number of the application and the heading indicates the number of pages of specification, including claims, and of sheets of. drawing contained in the application as originally filed. 'l he file of this application is available to the public tor inspectioii; reproduction may be purchased for 30 cents per sheet.

Applications published under the Defensive'Rublication Program have not been examined as to the merits of alleged invention. The Patent Oflice makes no assertion as to the novelty of the disclosed subject matter PUBLISHED APRIL 15, 1969 861 O.Gr, 70s

697,792 METHOD OF MAKING WHITE LIGHT HOLOGRAMS John S. Harper, Carmel, Harold H. Herd, Ossining, and Robert V. Pole, Yorktown Heights, N.Y., assignors to International Business Machines Corporation,Armonk, N.Y., a corporation of New York :2

Filed Jan, 15,1968. Published Apr. 15, 1969 Class 96-27 1 Sheet Drawing. 13 Pages Specification The manufacture of a hologram which is viewable in white light by a photographic printing method is disclosed. In the first step of theijmethod, a master hologram of a. conventional typefis placed in close contact with an unexposed photographic emulsion, which is the top layer of a multilayer structure. Alternatively, instead of a hologram, an article referred to as a holocoder may be placed in contact with the emulsion. The emulsion is the top layer of a structure including a rigid base having a smooth upper surface which is coated with a thin layer of gelatin and a thin layer of metallic silver. The multilayer structure is exposed through the hologram lby monochromatic light or by light emitted from a laser.

The light is spatially modulated by the hologram and then reflected by the silver layer which functions as a mirror, thereby forming spatially modulated standing waves in the unexposed emulsion,

In the next step, the hologram is removed and the re maining layers of the article are developed and fixed, The multilayer structure is then bleached so'that the metallic silver in both the emulsion and the silver layer is converted into silver bromide, which is then re-exposed to the laser light or the monochromatic light and re-developed, As a result, there is opaque granular silver both in the exposed area of the emulsions and in the silver layer which previously functioned as a mirror, The article thus pro= duced is a hologram which can be viewed in white lighta 

